Typewriter platen control mechanism



Dec. 2?, i949 R. E. GEARHART TYPEWRITER PLATEN CONTROL MECHANISM 3 Sheets-Sheet l Filed Jan. 14, 1946 INVENTOR, yl' @ear/95H1 BY Dec. 27, 1949 R. E. GEARHART TYPEWRITER PLATEN CONTROL MECHANISM Filed Jan. 14, 194e 5 Sheets-Sheet 2 /a fi? 4 //-U /0 Rain. 1,.; L M, W wg/vw. 1 W 5%@ /f Dec. 27, 1949 1 R. E. GEARHART v 2,492,793

TYPEWRITER PL'ATEN QONTROL MECHANISM Filed Jan. 14, 1946 3 Sheets-Sheet 5 f5 JW Patented Dec. 27, 1949 TYPEWRITER PLATEN GGNTROL MECHANISM Roy Ge'arhart,

Kansas City, vMo., A'assigner df one-halidso Allen Ghamb'ersf-Kansas vi(.`}i'y,""lVI'o. Applicationvlanuary 14, 1946Serial No.641,126

"inch 'spacesdepending on v'theadjustment of the `operating means. Anyintermediate spacing less than 'a lfullnorrnal line space must be made by 'fope'rat'ing the V-platen-release mechanism Aand -rnovin'g'fthe platen independently `of the shifting 4means by adjusting fthe `platen knobs. When 'the platen-is ythus shifted `the 'lines previously writ- Jten will usually befout `of register with the new tpositioning ofthe platen.

it the principal lobject ofthe .present inven- 'tion 'to provide "means for operating the platen,

Shaving detents vwherebythe platen' may. bemoved through relativelyfshort spaces, said 'spaces 'being equal, fractional Mdivisions o'f *the normal vvline wspace, whereby thel-pla-ten'maybe ,positively posi- :ltioned to Lsubstantially register with any typed yli-ne on the fp'aper. The accuracy of registration fwilldependfonthe number o'fequa'l divisions into fwhich-the normal line space is divided. 'The .largerthenumberof divisions, the more accurate Jthe registrations will be.

4'Another Yobieo't 4of the invention :is the provision 'o'i `a Iratchet yor detentiwhee'l 'having 'spring actuatedengagingmeans whereby the platen may '.-lbe positioned i-n anypredetermined fractional "division of 'the normal line-'space by vsimply rotat- -zing vthe platen by means `rof the attached Ahand dm'obs. f

.Another object of 'ftheinvention is the provi- `fsion of a :platencontrol Awhereby the 'typewritin'g operation may be 'started and continued from fsubstantially any point on f the `platen.

AAnother fob'j ec't 'fof this I 'invention is theprov'i- '.sion -of a platen control *having 'a plurality of 'detentstops for-a-single-:predetermined*line Ispace 'wherebythe p'la'ten'lmay be positionedtosubstantially -register lthe writing 'mechanism with any :previously written fline.

A -further object offtherinvention is a spiral gear drive 'between-the `platen 1shait 'and amanua11y operable fdiving i means.

Other 'objects tare @simplicity "and 'economy 1of (Cl. '13N-1514i :2 adaptability for .use 'in dividing the rotary movementfo'f the* platen Vintosubstantially 'microscopic divisions.

With `these objects in viewasrwell as other o'bjects which willappearfin the following speci- .,cation.reerence will be .had Ito the drawings, wherein:

Figure ,l isairagmentary plan view Yof a typewriterstruoture vincluding 'the ,platen and platen mounting and apla'ten control mechanism ernbodying this invention.

Fig.,2Jis an enlarged, sectional view 'taken on lineII-II of Fig.1l.

Fi'gfBlis an irre'gulansectional View taken on Fig. 4is 'an .irregular,^'sectional view taken on lineIV-*IVn'fFig2with parts shown 'in dotted `lines.

.Fig'B is an enlarged, fragmentary sectional view'taken online VV--V o'f Fig. 1.

, Fig.'6"'is a sectional view similar to that shown 'in Fig. 3 With'the 'operating -lever arm moved 'to an intermediate position.

. Eig. 7 is ,an inverted, fragmentary view of the :operating 'lever.

Fig. '8 "is an irregular, vertical sectional view rtaken on -line'fVIlI---VIII o'f Fig. 2.

; "91s a partially 'broken away ,plan view -o the back `lash take-up worm gear `shown vin solid 'lines 'in its normal position andfn dotted lines in the Worm .engaging position.

'Figgl iis 'aragnrentarm sectional view taken on line'X--ZX 'o'Fig 4.

Fig. '11 "is an inverted, vplan view of the top -disk.

"'Fig. VA12 'is aninverted -plan vView of 'the top Aplate and associated parts.

Fig. 13 is aplan view'o'f the driving disk.

`The-draw'ings'show only such parts of the com- 40 bined typewriter structure as are necessary .or an understanding of the manner in Which .the "gplaten 'control maybe applied to vthe typewriter. 'Tn'the voperation di a typewriter Ait is highly de- :s'irable to be able to start and continue writing 'at substantially anypoint on the .paperby simply rotating lhe platen `to position .by means ofthe mlatenikndbs.

"Throughout the several lviews like reference characters refer tto. :similar parts and the numeral '2|l.designatesv a'typewr'iter platen .iiXedly mounted l"im" 'rotation with .a .s'haf-t 22. 4One `end portion of vs`haft122 .is mounted in a .bearing 24 from w'hichfit may be .removed by simply lifting the :shaft upwardly. The .other end portion of shaft menstruation, ease fand-'accuracy of'operationan *22 `ismounted 'in abearing 2li which is integral with a gear housing 28. This housing is grooved on its opposite sides at 38 and 32 to receive tongues 34 of the typewriter carriage frame 36.

When so positioned in the bearings 24 and 26 the platen may be rotated in the usual manner of a typewriter platen to feed paper to the proper position for typewriting thereon. Tension rollers 38 operate in conjunction with the platen to position the paper during the writing operation.

Mounted in gear housing 28 is a split, back lash take-up worm gear 40 having two oifset gear portions 42 and 44. Gear portion 42 is rigidly attached to shaft 22 by means of a set screw 46, and gear portion 44 is normally carried in oset relation to portion 42 by means of a spring 48 which is anchored at 50 in the hub 62 of gear portion 42 and is tensioned to nor-- mally urge the teeth 54 and 56 of gear portions 42 and 44 out of registered alignment. Worm gear 48 is driven by a worm 58 mounted on a bearing post 66, which is rigidly mounted in gear housing 28 as clearly shown in Fig. 2. When the worm teeth are forced to position in the worm gear the teeth of gear sections 42 and 44 will be forced into substantially registering relation against the action of spring 48 which will tend to absorb all back lash and secure the platen against over-riding (see Fig. 9). As the gear teeth become worn spring 48 will cause relative movement of gear teeth 54 and 56 to facilitate proper tting of the teeth of the gear and worm to absorb all back lash. Referring to Figs. 2 and 8 it will be noted that spring 48 extends through an enlarged opening 55 formed in hub 52 to tightly engage in a hole 51 formed in gear section 44. The spring 48 is preferably made of piano wire and is of sulicient length to permit flexing to move the gear sections to avoid objectionable back lash, without fatiguing the spring. A spacing sleeve 48- mounted on shaft 22 and secured thereto by set screw 5| 'serves to prevent axial movement of gear section The worm 50 'is provided with a long hub 62 -1 having at its upper end a concentrically mounted annular disk 64. This disk is press-fitted on the hub, rotatable therewith and has a recess ,66 formed in its upper surface to receive a rigidly tted internal ratchet wheel 68 having a con- `outwardly by spring 82 which is securely attached to lever arm 14 at 84.

The upper face of gear box 28 is provided with 'a xed plate 86 notched at 88 to form a recess '86 for the reception of an arm 82 having a xed pin 94 which is pivotally mounted in a hole 96 formed in the wall of the gear box 28 (see Fig. 10)

This arm 82 carries at its free end a depending pin 88 on which is mounted for rotation a roller |08 which is adapted to engage between adjacent teeth of ratchet wheel 68 to serve as a detent to insure the proper line register. A spring |62 anchored at |04 in plate 86 is formed to contact the edge of arm 92 to constantly urge roller |88 to the seated position between said ratchet teeth. This action of the roller will ,68 and as shown are like holding the pawl out of engagement thus tend to always bring the platen to the desired line spacing position.

The Itop plate |86 is rigidly attached to the gear housing 28 by means of screws |08 to cover the roller arm 92 and has an annular portion ||6 which is disposed concentrically about bearing post 60. This annular portion ||0 has depending oiset arcuate portions that provide stop 2 for the limiting of the back movement of the operating lever and a stop ||4 that limits the forward movement of the operating lever. That portion of annular portion ||0 between stops ||2 and ||4 is positioned above disk 64 a sumcient distance to form a slot ||6 to permit of free working movement of Ithe operating lever arm 14 therein.

rlop plate |06 is provided with a boss ||8 bored l at |20 to receive the body of plug |22 and having a reduced hole |24 to receive the neck |26 of plug |22 which extends above base ||8 to receive the lever arm |28 which is secured thereto by means of pin |30. An eccentrically disposed pin |32 carried by the lower end of said plug extends into recess 66 in the path of travel of arm 82 and is normally positioned to vpermit free movement of the arm. When it is desired to make arm 92 inoperative, lever |28 is moved to position the pin |32 in the position shown in dotted lines in Fig. 4. When so positioned the pin will rest against a shoulder stop |34 formed in said arm.

Mounted concentrically about bearing post 60 is an annular disk |36 which registers with annular member ||0 and disk 64 and is held in position by shouldered sleeve |38 rigidly secured to post 60 by set screw |40. Sleeve |38 is recessed at |42 to register with an annular iiange |44 formed on top of operating lever 18 to present a compartment |46 to receive a lever operating spring |48. The'upper end of spring |48 is offset parallel with its axis at |50 to fit into a hole |5| formed in sleeve |38 and its other end is formed radially at |52 to engage a notch |54 formed in flange |44, Spring |48 is so set that it will always return the operating lever 14 to the normal or retracted position.

Referring to Fig. 3 which shows a section through disk |36, it will be noted that the disk is recessed at its under side to receive an annular ring |56 having a series of ratchet teeth |58 and an arcuate cam |60 of less radius than said series of ratchet teeth and disposed in diametrically disposed relation thereto. The ratchet teeth |58 are subtended by like radial angles as are teeth radial distances from the axis `of the bearingV pv st 60. It ls a requirement that the radial degrees of the lead of the teeth in the two sets of ratchet teeth be the same regardless of their relative radius for the purpose of proper timing of the operation of the operating pawl 18 as hereinafter set fort A vertically disposed pin |62 mounted in operating pawl 18 adjacent its free end rides on cam |68 when the operating lever 14 is in the retracted position thus with ratchet teeth 68; however, as the lever arm 14 moves forwardly, the pin |62 will drop oir the end |64 of the cam and the spring 82 will force it into engagement with the ratchet teeth to drive the platen through the desired degrees. In order to vary the degree of movement of the platen the disk |36 is rotated through the desired degree to position the end 64 of the cam relative to the retracted position of the operating pawl 18. By moving the disk |38 clockwise the platen will be 5 .caused to move through greater,- degiee eine@ .the pia .i-62'wil1 di, ora. .tam .|50 .Sooner forwardrnovement tVv s traveling a greater dietaaoe with the pavvl 1t .engaging ratehetteeth 6S- ll/leaiie for holding .diehlt ih a set. .position le provided in the 'forno of apawl -I v,6.1i pivoted inter.- .Ihediate its .ends .on a pin ,|68 mounted .ih ah .ear |69 integral Wit. top plate it adnrovided at its one end with a roller |19 which engages loef tween adjacent teeth .of ratchet teeth .|58- h spring Ill rigidly anchored .at |12 in thewall .of ring HIJ .formed to engage .one end of pavvl 1.615 .to oonstaatlir arge the" other end of the pawl .against the Series of ratohetteeth L58. whereby the .eier its may be .forcee @any .desires posi- .tion lov .engaging .the operating .handle |14.. Ari indicator pointer |16 mounted rigidly yon sleeve |311 le adapted .to register .with the gradiiations |13 .forrced .on they top .Surface of .disk les .see Fig. 1) l Eaoh end of Platen .Shaft 2.2 .is provided with :an operating knob |00 which `is secured thereto by means of set screws i|82 and by means oiwhch the platen 20 is manually rotated.

In the operation of this machine engages .the handle i114 to move disk |36 so that the index nger |16 will register with the desired gradnati-on |18. As previously set forth the operating lever arm 14 moves through the `same arc to engage the backstop I l2 and the forward stop H4, and as shown in the Figure 3 .the cam y|150 is set so that the operating pawl 80 will drop into the engagmnt .arid-.move the ratchet .$8 through a space equivalent to three .of the ratchet teeth so that the platen will be rotated through one predetermined standard Space, andwhen :so positioned, the typewriter may be operated to write what is lnonnally itermed a .singlespaced letter. As the handle i114 is operated .to serl disk A.|36 the detent ratchet teeth H515 will be engaged by the roller |10 `Whichvvill positively position said disk so that the index pointer |16 will :be in exact alignment with the desired graduation ,11.8. This machine vis `constructed to operate for single and double spacing only; however, it. might be -f easily increased to vtriple spacing Without any change in the general operation.y v

When ther roller |10 is in .registering position between adjacent teeth of the ratchet .|58 the roller |070 of ,armV 912 will be in register between adjacent teeth of driving ratchet 68. In other Words, the unit radial angle adjustment of disk |36 is altvays equivalent to the radial angle adjustment when the operating ratchet Wheel is moved one tooth. For this reas-on itis not material as to .the radial distance of the detents from the .axis of rotation of the disk, but is only de.- pendent upon the angle ofthe arc through which the detent is moved. When the disk |36 is set as just described the operating parts will take the position shown in Figure 3 so Athat as the lever arm 14 is moved to rotate .the operating pawl 6.2, the pavvl pin |62 Will ride on .the cam face |60 so that the pawl 18 will override the Ainternal ratchet teeth 63 until it drops off the shoulder i |64 of the cam to engage a ratchet, tooth at the center of its stroke. When so engaged the ratchet cam will be rotated three ratchet teeth or through one predetermined standard space. moved through the space of three -of the ratchet teeth the arm 14 will contact the stop ||4 thereby denitely limiting its movement.

It will be noted that the point of drop of the pawl 18 to the tooth engaging position is not critical since it may drop into a tooth and then the operator A moveto to the tooth engaging position .before actually starting the` .driving v,erreration.. The drivingof. the ratohetvvheel .6.8. .also drives .the worm or spiral gear 56 through a `like arc which in turn drives the .spiral gear 4f? thus driving .the platen Shaft .to Whioh the pla-.teh .20 is rigidly attached. It `for any reason the operator .desires to move the platen without operating the .lerer 14 he simply grips the platen Iknobs |80 yand turns the platen againstthe action of the detelltV |02, lf it is desired .to II nove the platen independent-1y of the deteht arm 92 he simply throws .thelever |28 in the direction indicated bythe arrow in Figure 1 until the pin u32 takes the position shown inv dotted lines Vin Figure 4, thn-s permitting a free movement of the platen to any desired position.

When the platen has been moved to .the desired position the operator simply moves the lever `|28 back to its original position thus releasing the arm 92 So that the rol-,ler will engage between adjacent teeth of the ratchet wheel v68. It fis quite apparent that should the roller |00 .of the arm 92, when released, be out of register said ratchet teeth, it Will immediately force the ratchet wheel to rotate through a `slight .degree to facilitate a proper registration.

Due to the iact that the normal standard spac: ing of a typewriter ls elllostahtlally 1/5 .of an ,and the movement of the ratchet Wheel V.0.8. to move the platen 1/c of an inch is .the space of three of said ratchet teeth, the movement .of the ratchet wheel through the space of .one too-th would moi/,e the Platen through the .Space oil?v fs .of one. inch; therefore, Should the roller 91.0 .ofarm 92,v when released, be substantially in radial alignment with the point of one of the .teeth 1of ratchet wheel im, the greatest distancethat it would .be required to move said ratchet Wheel .to the seated position would be through an angle that would move `the platen 1/36 of an inch. Dne tothe relatively long distance of travel of the pawlilrfin moving the platen through one space .or 1/6 of an inch, it will be apparent that the operating force required is considerably reduced as compared with the force required to operate the present-day typewriter .wherein the pawl moves l.the driving ratchet Vbut one tooth. By moving disk |35 clockwise as viewed in Figure 1, the cam |50 will .be moved :to a position whereby the operation of .the lever 1,4 vvill move the platen but of a space or l@ of an inch. By moving the ,disk 1.3.6 .anti-.clockwise one graduation the platen lWill be moved through one and one-third spaces or 2,4; ol? an inch.

Other variations in the stroke of the platen may be varied in like steps Vfrom JAS of .an inch to 1/3 of an inch.

It is quite apparent that the limit of change might be Varied .by simply adding a larger range of travel of the operating lever; furthermore, the neness of the distance of travel might be Varied by adding more graduations and corresponding detents between the adjacent standard spacing.

What I claim and .desire to protect by Letters Patent is:

1. lIn a typewriter platen control mechanism a platen shaft carrying a platen and mounted for rotation in a platen carriage frame, a Worm gear mounted on said platen shaft, a Worm mounted for rotation on a bearing post and carrying a concentrically positioned internal ratchet Wheel, fan operating arm mounted for rotation on said bearing post, a spring actuated pawl carried by said operating arm within said ratchet Wheel and adapted to engage and move said ratchet wheel, and adjustable means to hold said pawl out of engagement with said ratchet Wheel for a predetermined portion of the travel of said operating arm whereby the degree of operation of said worm gear is determined.

2. In a typewriter platen control mechanism a platen shaft carrying -a platen and mounted for rotation in a platen carriage frame, a driven gear mounted on said platen shaft, a drive gear operatively engaging said driven gear and mounted for rotation, an internal ratchet wheel rotatable with said drive gear, a pawl adapted to be rotated within and concentrically of said ratchet wheel to engage and move said ratchet wheel, and adjustable means operable to vary the ratchet engaging stroke of said pawl as said pawl is successively moved through like arcs.

3. In a typewriter platen control mechanism a platen shaft carrying a platen and mounted for rotation in a platen carriage frame, an internal driving ratchet wheel carried for'rotation on a bearing post carried by said frame, means operatively interconnecting said ratchet wheel with said platen shaftwhereby the latter is rotated to drive said platen, an operating lever carried on said bearing post for oscillatory movement between stops rigidly associated with said frame, a pawl carried pivotally by said operating arm and disposed within said internal ratchet wheel to engage the teeth thereof, the teeth of said ratchet wheel being spaced so that rotation of a single tooth turns the platen the smallest desired unit, and an adjustable cam whereby said pawl is held out of engagement with said ratchet wheel during any desired portion of the oscillation of said operating lever.

4. In a typewriter platen control mechanism a platen shaft carrying a platen and mounted for rotation in a platen carriage frame, an internal driving ratchet wheel carried for rotation on a `bearing post carried by said frame, a reducing gear train operatively interconnecting said ratchet wheel with said platen shaft'whereby the latter is rotated to drive said platen, an operating lever carried on said bearing post for oscillatory movement between stops rigidly associated with said frame, a pawl carried pivotally by said operating arm and disposed within said internal ratchet wheel to engage the teeth thereof, the teeth of said ratchet wheel being spaced so that rotation of a single tooth turns the platen the smallest desired unit, and an adjustable cam whereby said pawl is held out of engagement with said ratchet wheel during any desired portion of the oscillation of said operating lever.

5. In a typewriter platen control mechanism a platen shaft carrying a platen and mounted for rotation in a platen carriage frame, an internal driving ratchet wheel carried for rotation on a bearing post carried by said frame, means operatively interconnecting said ratchet wheel with said platen shaft whereby the latter is rotated to drive said platen, a spring detent associated with said frame to engage the teeth of said ratchet Wheel to permit only stepped rotation thereof, an operating lever carried pivotally on said bearing post for oscillatory movement between stops rigidly associated with said frame, a pawl carried pivotally by said operating arm, said pawl being disposed within said ratchet Wheel and normally urged'into engagement with the teeth thereof, the teeth of said ratchet wheel being so spaced that rotation of a single tooth turns the platen the smallest desired unit of rotation, and a cam ring disposed concentrically with said bearing post and forming a cam adapted to hold said pawl out of engagement with said ratchet wheel during a predetermined portion of the movement of said operating lever, said cam ring being manually rotatable about said bearing post in steps registering with the teeth of said ratchet Wheel.

6. In a typewriter platen control mechanism a platen shaft carrying a platen and mounted for rotation inra platen carriage frame, an internal driving ratchet wheel carried for rotation on a bearing post carried by said frame, means operatively interconnecting said ratchet wheel with said platen shaft whereby the latter is rotated to drive said platen, a spring detent associated with said frame to engage the teeth of said ratchet wheel to permit only stepped rotation thereof, an operating lever carried pivotally on said bearing post for oscillatory movement between stops rigidly associated with said frame, a pawl carried pivotally by said operating arm, said pawl being l' disposed within said ratchet wheel and normally urged into engagement with the teeth thereof, the teeth of said ratchet wheel being so spaced that rotation of a single tooth turns theplaten the smallest desired unit of rotation, a cam ring disposed concentrically with said bearing post, said cam ring being formed to present an internal cam adapted toV hold said pawl out of engagement with said ratchet wheel during a predetermined portion of the movement of said operating lever and having a series of internal teeth formed therein of equal angular pitch with the teeth of said ratchet wheel, and a spring actuated detent carried by said frame and engaging the teeth of said cam ring, said cam ring thereby being rendered manually rotatable in steps corresponding to the angular pitch of said ratchet wheel to regulate the number of units through which said ratchet wheel is turned for each stroke of the operating lever.

ROY E. GEARHART.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,568,426 Stickney Jan. 5, 1926 1,594,436 Vogt Aug. 3, 1926 1,817,252 Going Aug. 4, 1931 1,856,612 Zerick May 3, 1932 1,985,959 Stickney Jan. l, 1935 2,013,677 Stickney Sept. 10, 1935 2,206,831 Berthelsen July 2, 1940 

